US Bridges

I-90 over West Side Canal

Poor

Kittitas County, Washington · 14.7 E JCT SR 970 · Structure no. 0007904A0000000

Built
1966
59 years old
Condition
Poor
inspected February 2023
Type
Slab
Concrete
Length
38 ft
1 main span
Daily traffic
14,959
2023 count
Owner
State
State Highway Agency

About this bridge

I-90 over West Side Canal is a concrete slab carrying I-90 over West Side Canal in Kittitas County, Washington. It was built in 1966, so it is 59 years old, older than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 3 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 14,959 vehicles a day, roughly 23% of them trucks, projected to reach 18,102 by 2039. The structure is 38 ft (11.6 m) long and 40 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-90
CrossesWest Side Canal
Location14.7 E JCT SR 970
RouteInterstate 90
CountyKittitas County
StateWashington
Coordinates47.05749, -120.67624
Functional classRural Principal Arterial - Interstate

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck3 SeriousLoss of section, deterioration, spalling or scour have seriously affected primary structural components.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionFebruary 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating94 US tons
Inventory rating55 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20 + Mod
Structure length38 ft (11.6 m)
Longest span35 ft (10.7 m)
Deck width40 ft (12.2 m)
Roadway width36 ft (11.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic14,959 (2023)
Projected traffic18,102 by 2039
Trucks23%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$722,000 (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was I-90 over West Side Canal built?

It was built in 1966, making it 59 years old in 2025.

What condition is I-90 over West Side Canal in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in February 2023.

How much traffic does I-90 over West Side Canal carry?

About 14,959 vehicles per day (2023 count), of which roughly 23% are trucks.

How long is I-90 over West Side Canal?

The structure is 38 ft (11.6 m) long with a longest span of 35 ft (10.7 m) and a deck 40 ft wide.

Who owns I-90 over West Side Canal?

It is owned by the State Highway Agency.